With the constant development of the wireless charging technology, using the wireless charging system to provide power for electric devices becomes a development direction of electric device charging, with respect to the wired charging ways, the wireless charging has significant advantages.
FIG. 1 is a schematic diagram of the basic structure of a Wireless Power Transfer (WPT) system, as shown in FIG. 1, the system comprises: a Power Transmit & Control circuit (PT&C), a contactless transformer & compensation circuit (CT&C), a power Pickup & control circuit (PP&C). Wherein, the PT&C comprises: a power factor controller and a full-bridge inverter, wherein the full-bridge inverter using a soft switch of the inverter bridge has a requirement of input impedance characteristic after the inverter bridge on the system which includes the CT&C after CT&C is performed; the CT&C comprises: a transmitting coil and a receiving coil; wherein the transmitting coil consists of a magnetic core, a coil 1 and a capacitor C1 connected in series, and the receiving coil consists of a magnetic core, a coil 2 and a capacitor C2 connected in parallel; the PP&C comprises: a rectifier and a DC-DC converter. When the wireless power transfer system is used to wirelessly charge an electric device, usually the transmitting coil of the CT&C is placed on the ground or underground, while the receiving coil is mounted under the electric device body.
When using a wireless power transfer system to charge an electric device, its transmitting coil and receiving coil need to meet a certain positional relationship to ensure a stable and efficient operation of the system. Taking an electric vehicle as an example, FIG. 2 is a diagram of a positional relationship of the transmitting coil and the receiving coil, as shown in FIG. 2, in an actual implementation process, due to driver skill differences and electric vehicle body differences, when an electric vehicle parks and is being charged, the X-axis offset a, the Y-axis offset b and the Z-axis offset c of the receiving coil 1 and the transmitting coil 2 under the vehicle body cannot guarantee that they meet the positional relationship of the input impedance characteristic after the inverter bridge and the CT&C voltage gain characteristic required by wireless charging. In order to achieve normal charging of the wireless power transfer system, currently a position detecting system and a mechanical adjusting device are used, that is, each wireless power transfer system is provided with a position detecting system and a mechanical adjusting device for adjusting the height and coordination of the transmitting coil, wherein, the position detecting system is used for determining the positional relationship between the transmitting coil and the receiving coil, and the mechanical adjusting device is used for adjusting the positional relationship of the transmitting coil and the receiving coil to meet the wireless charging requirement.
In the wireless charging process, if a traditional mechanical adjusting device is used in a long term, the maintenance is difficult when it fails. If the mechanical adjusting device is provided at the position of the vehicle body adjustment receiving coil, the maintenance problem is still not negligible; and more expenses need to be added for the industrial design of the vehicle body.
Through the abovementioned description, it can be found that, when using the wireless power transfer system to wirelessly charge an electric device, the wireless power transfer system achieves the position adjustment of a transmitting coil through a long-term use of the mechanical adjusting device, which has the problem that the maintenance is difficult.